Method of forming a coating application roll

Abstract

A method for making an application or dip roll for applying a coating, such as an aqueous clay and starch solution, from a trough, onto a moving web on a papermaking or coating machine. The roll comprises a roll cylinder having a hard, outer surface which is not subject to attack by the coating to be used. A plurality of minute indentations are formed in the outer surface of the roll to enhance the transfer of coating from the trough to the roll. Preferably, the roll is first provided with a smooth surface finish. Then the plurality of indentations are formed by shot blasting the outer surface of the roll with hard shot. If a shot of a material subject to attack by the coating is used, the roll may be subsequently blasted with another material, not subject to such attack, so as to remove any fragments of the first shot that might have become embedded in the roll.

What is claimed is: 
     
       1. A method of making a coater dip roll for use directly adjacent a moving paper web, consisting of the steps of: selecting a cylinder made of a corrosion resistant material;   providing said cylinder with an initial outer surface finish of substantially 16 microinches RMS;   shot blasting the outer surface of said cylinder with steel shot 0.030 to 0.060 inches in diameter and having a hardness of 40 Rockwell C or greater;   continuing said shot blasting until said outer surface of said cylinder has a hardness of 30 Rockwell C or greater and said outer surface has a plurality of cup shaped indentations providing a surface of 300 to 500 microinches RMS;   blasting said outer surface of said cylinder with glass beads to remove any embedded fragments of the steel shot, and   rotatably mounting said cylinder in a coater and directly adjacent the moving paper web.   
     
     
       2. The method of claim 1, wherein said selection is made from stainless steels, and said glass blasting is done with beads of 100 to 200 mesh in size.